Identifying an indicator compound for progress monitoring during in-situ thermal treatment of coal tar and creosote

IF 3.5 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Journal of contaminant hydrology Pub Date : 2025-03-09 DOI:10.1016/j.jconhyd.2025.104543

Liam M. Price, Ariel Nunez Garcia, Kevin G. Mumford

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Abstract

In situ thermal treatment (ISTT) has been used to treat sites impacted by coal tar and creosote when stringent remediation objectives must be met over short timeframes. There is a need to identify an indicator compound that can be used to track progress during the treatment of these complex semi-volatile non-aqueous phase liquids (NAPLs) to complement soil sampling typically conducted once treatment is complete. This study outlines an approach to track ISTT progress and support shutdown decisions based on mass removal objectives using a series of laboratory experiments to investigate changes in semi-volatile NAPL composition during thermal treatment. Sand, water and semi-volatile NAPL were heated, and the recovery of polycyclic aromatic hydrocarbons (PAHs) was monitored by sampling and analysis of condensate. PAHs were predominantly removed between 260 °C and 455 °C, with early-stage condensate composed of higher volatility PAHs and later-stage condensate composed of lower volatility PAHs. Experimental results showed that intermediate-volatility PAHs (e.g., phenanthrene) could be used as an indicator compound to infer treatment progress with respect to both higher and lower volatility PAHs. Monitoring an indicator compound during ISTT of semi-volatile NAPL could provide higher confidence in treatment progress than conventional monitoring techniques and allow for more accurate shutdown decisions.

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来源期刊

Journal of contaminant hydrology 环境科学-地球科学综合

CiteScore

6.80

自引率

2.80%

发文量

129

审稿时长

68 days

期刊介绍： The Journal of Contaminant Hydrology is an international journal publishing scientific articles pertaining to the contamination of subsurface water resources. Emphasis is placed on investigations of the physical, chemical, and biological processes influencing the behavior and fate of organic and inorganic contaminants in the unsaturated (vadose) and saturated (groundwater) zones, as well as at groundwater-surface water interfaces. The ecological impacts of contaminants transported both from and to aquifers are of interest. Articles on contamination of surface water only, without a link to groundwater, are out of the scope. Broad latitude is allowed in identifying contaminants of interest, and include legacy and emerging pollutants, nutrients, nanoparticles, pathogenic microorganisms (e.g., bacteria, viruses, protozoa), microplastics, and various constituents associated with energy production (e.g., methane, carbon dioxide, hydrogen sulfide). The journal''s scope embraces a wide range of topics including: experimental investigations of contaminant sorption, diffusion, transformation, volatilization and transport in the surface and subsurface; characterization of soil and aquifer properties only as they influence contaminant behavior; development and testing of mathematical models of contaminant behaviour; innovative techniques for restoration of contaminated sites; development of new tools or techniques for monitoring the extent of soil and groundwater contamination; transformation of contaminants in the hyporheic zone; effects of contaminants traversing the hyporheic zone on surface water and groundwater ecosystems; subsurface carbon sequestration and/or turnover; and migration of fluids associated with energy production into groundwater.